This invention relates to a needleless access device for use with liquid flow and administrative apparatus for medical purposes.
The use of hypodermic needles to inject or withdraw fluids in medical applications has been standard practice for a number of years. Even where a patient already has an IV tubing set connected to a vein, hypodermic needles are frequently used to inject fluids into the IV tubing. Often a "Y connector" with a septum is provided in the tubing set for this very purpose. The needle is used to puncture the septum to administer the drug or other fluid, and the septum then sufficiently seals the opening to prevent airborne bacteria from entering the system. Septums are also common on drug vials, where the needle is inserted to withdraw a quantity of the drug.
The widespread use of hypodermic needles leads to numerous needle-stick accidents. These are not only painful, but if the needle is contaminated, could cause serious disease or complications in the needle-stick victim.
To prevent such accidents, needleless access devices have been designed. These devices typically include a cap having an inlet opening and a body with an outlet opening. In some instances, the devices are provided with a piston that, in its normally closed position, seals the inlet opening of the device to prevent bacterial contamination and maintain sterility.
U.S. Pat. No. 5,439,451 discloses a Capless Medical Backcheck Valve for allowing liquid flow into an IV line. The backcheck valve includes a flexible elastomeric piston that has a flexible tubular wall. The use of such a flexible piston in a needleless access device tends to increase the interior hold-up volume within the device. Further, the flexible tubular wall may tend to impede fluid flow. In addition, the material required to make a flexible piston may require lubricants to function properly.
In some instances, blood and possibly other fluids may enter a needleless device through the outlet after the device has been used to administer fluid into IV tubing. This phenomenon is commonly referred to as reflux.
There is thus a desire for a needleless medical system, where a fluid can be injected or aspirated with minimal reflux, while minimizing hold-up volume, allowing unimpeded fluid flow and requiring no additional lubricants to function properly.